TOKYO (Reuters) - Japan has begun treating severely ill COVID-19 patients with Gilead Sciences Inc?s coronavirus drug remdesivir, days after granting emergency approval to the medication the company is supplying as part of its pledged donation. Japan?s approval a week ago of remdesivir as a treatment for COVID-19 followed the U.S. Food and Drug Administration?s emergency authorization of the antiviral drug on May 1. At that time, Foster City, California-based Gilead reiterated plans to donate 1.5 million doses of remdesivir - enough to treat at least 140,000 patients - ?to help address the urgent medical needs posed by this pandemic around the world.? The U.S. Department of Health and Human Services on Saturday said Gilead had committed to supply U.S. hospitals with about 607,000 vials of remdesivir, about 40% of the total 1.5 million-vial donation. After doctors had questioned the transparency of the allocation process, the federal agency said state health departments would distribute the intravenous drug. Gilead has not responded to requests for information about further global allocation plans. Company spokeswoman Seiko Noma confirmed in an email late Wednesday that an undisclosed portion of remdesivir vials have been donated to the Japanese government. ?There are far more patients that may benefit from remdesivir than there are doses to go around.? Dr. Michael Ison, professor of infectious diseases at Northwestern University Feinberg School of Medicine, said in a Journal of the American Medical Association editorial on Thursday. The Infectious Diseases Society of America on Thursday asked to meet with Dr. Deborah Birx, the White House Coronavirus Task Force coordinator, ?to address ongoing questions regarding access to remdesivir and to inform planning for use of the drug.? The medical group said uncertainty over those issues was interfering with patient care. Japan Ministry official Yasuyuki Sahara said in an e-mail on Thursday that the U.S. firm?s treatment has been distributed to hospitals in Japan since May 11 and is being used for patients in intensive care or on ventilators. Sahara said the amount of remdesivir delivered by the drugmaker was not public information, and global supplies were ?quite limited?. Japan has had about 16,000 infections and 687 deaths from the coronavirus outbreak, much lower than many industrialised nations. The number of serious cases requiring ventilation was 259, according to the latest figures from the health ministry. The United States has nearly 1.4 million coronavirus infections and almost 84,000 deaths. With no other approved treatments for COVID-19, interest in remdesivir is growing around the world. Gilead on Tuesday said it had signed non-exclusive licensing pacts with five generic drugmakers based in India and Pakistan to expand the supply of remdesivir in more than 120 mostly low-income countries in Southeast Asia, Africa and other parts of the world. Gilead said the drug has improved outcomes for people suffering from the respiratory disease and has provided data suggesting it works better when given in the early stages of infection. Preliminary results from a trial led by the U.S. Institutes of Health showed remdesivir cut hospital stays by 31% compared with a placebo treatment, although it did not significantly improve survival. Remdesivir, which previously failed as a treatment for Ebola, is designed to stop some viruses making copies of themselves inside infected cells.